*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    text-decoration: none;
    font-family: Arial, sans-serif;
}

html {
    /* 整个html大小为72.5%，1rem = 11.6px，以后只需要修改这里就能适应所有尺寸 */
    font-size:72.5%
}

.container {
    width: 100%;
    height: 100vh;
    background: linear-gradient(rgba(31, 7, 7, 0.7), rgba(0,0,0,0.7)), 
        url(image/bg.png) center no-repeat;
    background-size: cover;
    /* 必须用rem做单位，否则旋转会出问题 */
    perspective: 100rem;
}

.forms-wrapper{
    transform-style: preserve-3d;
    position: absolute;
    top: calc(50% - 17.7rem);
    left: calc(50% - 25rem);
    transform: rotateY(10deg);
    transition: transform 0.5s, left 0.5s;
}

.forms-wrapper form{
    width: 50rem;
    height: 35rem;
    background-color: rgba(40, 114, 108, 0.925);
    display: flex;
    /* 纵向排列 */
    flex-direction: column;
    /* 均匀分配空间 */
    justify-content: space-around;
    align-items: center;
    /* inset 内嵌阴影 */
    box-shadow: 0.1rem 0.1rem 0.1rem #ccc inset, -0.1rem -0.1rem 0.1rem #ccc inset;
    /* 表单重叠 */
    position: absolute;
}

.signup-form{
    transform: rotateY(270deg) translateZ(25rem) translateX(-25rem);
}

form a{
    position: absolute;
    top: 2rem;
    background-color: #fff;
    font-weight: 600;
    text-transform: uppercase;
    color: rgba(40, 114, 108);
    letter-spacing: 0.2rem;
}

.signup-btn{
    left: 2rem;
    padding: 0.5rem 1rem 0.5rem 3rem;
    /* 倒角 */
    border-radius: 100% 0.5rem 0.5rem 100%;
}

.signin-btn{
    right: 2rem;
    padding: 0.5rem 3rem 0.5rem 1rem;
    border-radius: 0.5rem 100% 100% 0.5rem;
}

.forms-wrapper.change{
    transform: rotateY(70deg);
    left: calc(50% + 25rem);
}

form h2{
    font-size: 2.3rem;
    text-transform: uppercase;
    letter-spacing: 0.2rem;
    color: #fff;
}

.inputs-wrapper{
    display: flex;
    flex-direction: column;
}

.inputs-wrapper input{
    width: 25rem;
    height: 3rem;
    padding: 0.5rem 1rem;
    margin: 0.5rem 0;
    /* 背景色透明 */
    background-color: transparent;
    border: 0.1rem solid #fff;
    border-radius: 5rem;
    color: #fff;
    letter-spacing: 0.1rem;
    outline: none;
}

.inputs-wrapper input::placeholder{
    color: white;
    font-weight: 300;
}

.inputs-wrapper input[type = 'submit']{
    background-color: white;
    text-transform: uppercase;
    color: rgba(40, 114, 108);
    font-weight: 900;
    /* 指针变为手指 */
    cursor: pointer;
}